Types of chargersThe type of charger you choose must be compatible with the battery
chemistry. Sealed Lead Acid and Gel batteries use the same type of charger. The
charge process is essentially done in three stages:
1) Fast Charge - at the beginning of the charge cycle, the charger delivers its
maximum current. Higher current removes sulfation from the battery plates.
Sulfation is the solid yellow-brown material you can see sticking to the lead
plates. It blocks the chemical reaction between the electrolyte and the plate,
which reduces the battery's capacity. Too much current will boil the
electrolyte, so be sure to choose a charger that produces current within the
manufacturer's rating for the battery. Generally, the higher the battery's
capacity, the more current it can handle.
2) Constant current or constant voltage - depending on the type of charger, a
lower amount of voltage or current is supplied as the battery reaches its rated
voltage. The lower amount of power assures that the electrolyte is not boiled
and continues until the battery is fully charged.
3) Float or trickle - a small amount of current is supplied to keep the battery
at full capacity.

Intelligent Chargers
So-called intelligent chargers can be left on indefinitely. All chargers sold by
ElectricRider can be left connected indefinitely. However, it's a good idea to
disconnect the charger from the battery pack and the AC power outlet when the
batteries have reached capacity because electricity is still used for the float
cycle and there is no reason to waste the power. Some chargers will very slowly
discharge a battery if removed from AC power and not disconnected from the
battery pack, so always disconnect from the pack when disconnecting from AC.

Chemistries besides lead acid
Other batteries such as NiMH, Lithium Ion, and LiFePO4 require a different
charging profile than lead acid. Always choose a charger specifically made for
the battery pack you are using. Use of the wrong charger can destroy the
battery, the charger, and even cause a fire. Lithium-based battery packs have a
circuit board called a Battery Management System, and the charger must be
compatible not only with the battery chemistry, but also with the BMS.